With increasing data transmission speed, higher frequency band signals may be reduced along transmission lines. In some cases, swing ranges of higher frequency signals may decrease more than lower frequency signals. To compensate, a pre-emphasis technique in which a swing range of higher frequency signals may be set larger than a swing range of low frequency signals may be used.
In an open drain mode of a current-mode line driver used in conventional high speed transmitters, a relatively large amount of current may be needed to extend swing range. Therefore, a half-VDD line driver may be used to decrease current. The half-VDD line driver may reduce power consumption in half. Such a half-VDD line driver, however, may not achieve a desired bandwidth.